A random protein-creatinine ratio accurately predicts baseline proteinuria in early pregnancy

Objective: Data surrounding the use of a random urine protein: creatinine ratio (PCR) in the diagnosis of preeclampsia is conflicting. We sought to determine whether PCR in early pregnancy can replace the 24-hour urine collection as the primary screening test in patients at risk for baseline proteinuria. Methods: Women requiring a baseline evaluation for proteinuria supplied a urine sample the morning after their 24-hour collection. The PCR was analyzed as a predictor of significant proteinuria (>= 150 mg). A regression equation to estimate the 24-hour protein value from the PCR was then developed. Results: Sixty of 135 subjects enrolled completed the study. The median 24-hour urine protein and PCR were 90mg (IQR: 50-145) and 0.063 (IQR: 0.039-0.083), respectively. Fifteen patients (25%) had significant proteinuria. PCR was strongly correlated with the 24-hour protein value (r = 0.99, p<0.001) and highly predictive of significant proteinuria (AUC = 0.86). A PCR cut-point of 0.079 yielded a sensitivity of 93.3% and a specificity of 57.8%. The resulting regression equation [total protein = 46.5 + 904.2*PCR] accurately estimates the actual 24-hour protein (95% CI: +/-88 mg). Conclusion: A random urine PCR accurately estimates the 24-hour protein excretion in the first half of pregnancy and can be used as the primary screening test for baseline proteinuria in at-risk patients.